Necessary parameters for diagnosis, epidemiological and immunological investigation of blastomycosis are not available. An alkali-soluble, water-soluble (ASWS) extracted of the yeast phase cells of Blastomyces dermatitidis previously was shown to elicit a specific delayed type hypersensitivity (DHS) response and recently was shown to be sensitive in detecting cell-mediated responses when tested in in vitro tests; migration inhibition (MIF) and lymphocyte transformation (LT) assays. The following additional studies of the antigen are planned: (1) Reproducibility of sequential preparations of the ASWS antigen and the comparison of ASWS preparations from various B. dermatitidis isolates will be undertaken. These preparations will be compared chemically and tested in vivo (skin test) and in in vitro MIF and LT. (2) Further characterization of a specific antigenic component will be undertaken using enzymatic digests of ASWS and the potency of these components will be tested for their skin test reactivity. (3) Similar alkali hydrolysis will be used on the mycelial phase of B. dermatitidis. The composition of this mycelial ASWS will be compared to the yeast ASWS for chemical similarities and tested in vivo (skin test) and in vitro (MIF and LT). (4) The antigen will be tested in the standard serological tests, complement fixation, immunodiffusion, and counter immunoelectrophoresis. Finally, B-ASWS will be used in conjunction with histoplasmin and blastomycin to study the possibility of passive transfer of immunity in animal models of experimental blastomycosis.